Indian Journ<ll of Fihre & Textile Research Vol. 28, June 2003, pp. 1 47- 1 49

Processibility of Nigerian kapok fibre

B M 0 Dauda" & E G Kolawole

Department of Textile Science <lnd Technology, Ahm<ldu Bello University, Zaria. Nigeria

Received 1 9 September 2001; revised received alld accepted 22 May 2002

The spinning of Nigerian kapok fibre and its blend with colton fibre has been studied. It i s observed that the spinning of 1 00% kapok fibres beyond lap formation stage i s not possible, while the spinning of kapok fibre blended with at least 50% cotton fibre is largely successfu l . The yarn regularity and tenaci ty decrease whi le the yarn extensibi l i ty i ncreases with the incre<lse in bpok content in the blend. The total cost of production of the yarns decreases significantly as the kapok content in the blend increases.

Keyword: Cotton fibre, Kapok fibre, Rotor-spun yarn, Y<lrll i rregul<lrity

1 Introduction Kapok fibre is obtained from the seedpod of kapok

tree (Ceiba petandra l .3) found in India, Java, Indonesia and in some sub-Sahara African countries including Nigeria. The kapok tree starts producing fruits after two years of planting and according to the locals in Zaria (Nigeria), the tree fruits annually for at least 50 years.

Kapok fibre has relatively high non-cellulose content and a very smooth surface. This has discouraged its use as a texti le fibre because it was presumed that it is extremely difficult or impossible to spin kapok fibres into yarn. However over th� years, the fibre was used in l ife jackets and for temperature and sound insulation2• Little amount of the kapok fibre produced in Nigeria is used as stuffing in local pillows and mattresses and the large amount is left as wast�, causing a nuisance on motorways. Earl ier study of the Nigerian kapok has been restricted to the characterization of the fibre) . The present investigation was therefore aimed at spinning the kapok fibre into yarn with the ultimate aim of using it as a cheap substitute or supplement to the cotton in fabric productions due to the ever increasing cost of imported cotton and the abatement of local production of cotton Iint4.

2 Materials and Methods 2.1 Preparation of Yarn Samples

The physical and chemical properties of both

" To whom <lll the correspondence should be addressed. Phone: 08037024748; Fax: 00234-069-330565;

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cotton and kapok fibres used are shown in Table 1 . The second passage drawn slivers (3 .82 ktex) of different cotton:kapok blends, viz 20: 80, 30:70, 40:60. 50:50, 60:40, 70:30 and 80:20, were separately spun into yarns of different counts [35 tex and 40 tex (nominal)] , each with the nominal twist levels of 6tpcm and 7tpcm. A rotor spinner (Czechoslovakian B0200) operating under normal mill conditions at a rotor speed of 40,000 rpm and opening rol ler speed of 6000 rpm was used. The rotor diameter was 55 .5mm.

2.2 Tests

The yarn count was determined in accordance with BS 201 0 - 1 953 guidel ines. The single yarn tenacity and breaking extension were measured on the Uster single thread strength testing machine using a 50cm test length. A carriage weight ranging from 600g to 1 500g was used based on the behaviour of each type of yarn. Fifty tests were carried out for each yarn sample. Yarn regularity was measured using the Uster evenness tester running at a speed of 25 yds/min. The detection of faults in the spun yarns was also carried

Table 1- Characteristics of Zaria cotton <lnd kapok

Characteristic Cotton4 Kapok

Cel iulose, % 93.0 63.50

Lignin N i l 1 3% of fibre mass

Pcntosans 5% of fibre mass 23% of fibre mass

Fibre length, mm 26.64 27.08

Moisture content, % 8.50 1 0.80

External structure Convoluted Cylindric<ll. very smooth

Density, g/cm 1 .53 0.29

148 INDIAN J. FIBRE TEXT RES., JUNE 2003

out with the aid of the Uster classimat II yarn fault c lassifying installation. Apparent twist in all the yarns was estimated using the Barker twist contraction method5 and fifty tests were carried out for each yarn sample.

3 Results and Discussion Due to the unacceptable levels of yarn breakage

experienced while spinning sl ivers with less than 50% cotton content, the yarns with at least 50% cotton content were spun. The results presented are for 35 tex / 6 tpcm yarns. The trends in the properties of other yarns (not reported here) were essential ly simi lar.

3.1 Twist Assessment

The twist efficiency was calculated on the basis of the ratio of measured yarn twist to the machine twist. The results (Table 2) show that for all the yarns, except for 50/50 cotton:kapok, some of the machine twist has been lost. This is due to the known fact that the fibre sl ippage occurs at the yarn formation point within the rotor. The fact that the cotton and kapok

Table 2 - Effect of blend ratio on yarn twist

Blend ratio Twist, q�cm Twist effic iency (Collon:Kapok) Nominal Actual CV% %

1 00:0 5.26 5. 1 7 5.5 1 98.3 80:20 5.74 5 . 6 1 5.57 97 .74 70:30 6.38 6.36 4.22 99.7 60:40 6.86 6.73 8.55 98. 1

50:50 7.65 7.74 4.82 1 0 1 . 1 8

Table 3 - Effect of blend ratio o n yarn l inear density

Blend ratio Tex CV% Tex CV% (Cotton: Kapok)

1 00:0 35.40 0.94 40.69 0.855

80:20 35.22 1 .24 40.36 0.824

70:30 35.35 1 .95 40.0 1 0.895

60:40 35.29 1 .7 1 40. 1 2 0.758

50:50 34.95 2.25 40.64 0.996

Mean CV% 1 .62 0.865

have different surface texture and hence different surface frictional characteristics may have caused the differential twist pattern observed. The probable cause of the apparent increase in twist efficiency for the 50:50 cotton:kapok yarn is twist contraction because it has the highest value of twist among all the yarns.

3.2 Yarn Count Assessment

It is apparent form the mean CV% of tex (Table 3) that as the yarn becomes finer, the count uniformity gets worse. The better uniformity in count for 40 tex yarns as compared to that for 35 tex yarns may be due to the greater number of doublings that occurred inside the rotor as the fibres are laid and reassembled.

3.3 Yarn Irregularity

Table 4 shows a progressive deterioration in yarn regularity with the increase in kapok content in the blend. This observation is further corroborated by the Uster classimat fault rate comparison test result (Table 4) which shows that immediately when 20% kapok is added to 1 00% cotton yarn, there is a 300% increase in the total number of fau lts per 100,000m. While the difference in the number of faults per fixed length between 80:20 & 70:30 and 70:30 & 60:40 cotton:kapok is smal l (2.5% and 7% respecti vely), the deterioration in yarn qual ity (regularity) is more for 50:50 cotton:kapok with 49% increase in number of yarn faults. This may be the cause of difficulty experienced earlier in spinning cotton/kapok blended yarn having more than 50% kapok. This may be because of the fact that the relatively low density of kapok fibres does not lend the fibres to assemble properly as expected in the col lecting surface of the rotor.

3.4 Yarn Tenacity

A yarn under stress fai l s due to either fibre slippage or actual fibre breakage within the yarn structure. Thus, as the kapok content increases, as expected, the relative fibre slippage within the yarn structure increases, leading to reduction in yarn strength

Table 4 - Effect of blend ratio on Uster irregularity, yarn fault, tenacity and breaking extension

Blend ratio Uster irregularity Yarn f aultsl I OO,OOOm Tenacity Breaking

(Cotton:Kapok) (U%) (Classimat) g/tex extension, %

1 00:0 1 0.32 280 1 8 .3 9.8

80:20 1 1 . 1 2 1 1 04 1 6.8 1 0.3

70:30 1 1 .28 1 1 36 1 5 .2 1 0.9

60:40 1 1 .3 1 1 2 1 6 1 2 .2 1 2.2

50:50 1 2 .67 1 800 9.6 1 7.5

DAUDA & KOLAWOLE : PROCESSIBILITY OF NIGERIAN KAPOK fiBRE 1 49

(Table 4). Sunmonu and Abdullahi3 observed that the kapok is a weak fibre; this factor again contributes to the decreasing strength observed with the increase in kapok content. The yarn irregularity also contributes significantly to the observed decreasing trend in tenacity because the thin places along the length of the yarn serve as weak spots that easily yield.

3.5 Breaking Extension

The low density of kapok fibre leads to folding/entanglement of fibres. Therefore, when the yarn is extended, the straightening of folded fibres and slippage (kapok is very smooth) give rise to higher breaking extension (Table 4).

3.6 Cost Analysis

Based on the average local production cost of 1 kg of cotton yarn6 and the current cost of cotton and kapok fibres (N 120.09/kg and N 5 .00/kg respectively), the expected reduction in yarn production cost is given below:

80:20 cotton:kapok -20.00% reduction in cost. 70:30 cotton: kapok -28.75% reduction in cost. 60:40 cotton:kapok -38.33% reduction in cost. 50:50 cotton:kapok -48.00% reduction in cost.

4 Conclusions 4.1 Despite the adoption of humidity control scheme7, the 100% kapok could not be processed beyond the lap stage. However, the kapok fibres could be spun when blended with cotton in the ratio of 50:50. A blend with less than 50% cotton content can only be spun with extreme caution.

4.2 The blending of kapok with cotton results in deterioration in yarn functional properties. However, despite some loss in yam quality, the significant reduction in production cost can be achieved by blending some kapok with cotton. Since cotton:kapok yarns are relatively weak, they could be used as weft yarns in weaving where the yarn is subjected to low stress and its bulkier nature will be an advantage since one of the desired characteristics in weft yarns is its good covering power.

Acknowledgement

The authors are thankful to Raw Materials, Research and Development Council, Federal Ministry of Science and Technology, Abuja, Nigeria, for providing the financial support. Thanks are also due to the management of Kaduna Textiles Limited, Nigeria, for providing facilities for lap and silver production.

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varieties to chemical processing, M Sc. dissertation, Ahmadu Bel lo University, Zaria, Nigeria, 1 997.

5 Booth J E, Principles of Textile Testing (Newness-Butterworth Publishers, London), 1 968, 24 1 .

6 Report on Techno-Eco."!omic Survey on Textiles (Raw Materi­als Research and Development Counci l , Abuja), July 1 998.

7 Niclds M, J Text Inst , 75 ( 1 984) 645.